I am a vet tech and would just like to make a comment. You can buy Advantage at other places besides the vet. It could be found at practically all chain pet stores and it can last longer than 4 weeks. You also can split one tube on two cats or buy a dog one and use that for four cats. That will save you a lot of money in the end. Also whenever you use this product you must wash your hands. If your pet accidently licks the product it shouldn't couse any harm. Also I would not reccommend using Advantage on rabbits and using it on ferrets can kill them. I would suggest using a flea shampoo and then an herbal flea collar, or just keep your rabbit indoors. They are easily potty trained to a litter box. Do not use clumping litter however as it can stick to the penis and cause problems.